Builder Issue

Hi, My father has given our 30years old property to Builder in 50-50 partnership deal. initially we have received partially amount from the builder and after an year he handover one Flat to us. As per 50-50 deal,He has built extra Sqt feet and made 3 flats and two flat should be handover to us. We were not able to repay the initial amount which my father has borrowed from him initially. He denied to give second flat for that which is our share (50 percent of the flat cost only was given to us initially) after selling the second flat which was our share he denied giving money rest of the money saying it is the interest which he wanted and He did not pay for the extra square feet which he has built. We are actually tensed because of loosing the property and money as well. What we hold is one flat and the initial amount which he paid . From our land he has sold all four flat and denying to payamount which he earned through selling our share flat and for the extra square feet. Can this be dealt legally. Will we get our money back.